The present invention relates to a machine for positioning tyre beads. It also relates to a method using said machine.
The conditions in which tires are required to travel are becoming more and more harsh, and whatever said conditions the beads of a tire have to be positioned correctly on the seats of the mounting rim thereof. The clamping thereof on seats is becoming more and more important, and the mounting of a tire on its rim is becoming more and more difficult, even when mounting machines are used. The poor mounting operations which are observed result in defective positioning of the beads, with the bead seats not bearing on the rim seats over their entire surfaces. These defective positioning operations may cause dislodging of beads if the case arises.
In order to be able to deliver to vehicle manufacturers only mounted assemblies in which the tires have beads which have been correctly positioned, Japanese application 64/03683 describes a method for positioning tire beads which consists in exerting a pressure on the two sidewalls of the inflated tire, so as to detach the beads from the rim flanges and seats, the internal pressure of the tire correctly repositioning them as soon as the pressure force on the sidewalls is removed. The devices provided for applying such a pressure to the sidewalls comprise either two rings, each ring being placed on one side of the tire, or rollers, each roller effecting a circular path on each sidewall of the tire.
Such a device is advantageous when effecting the positioning of tyre beads of the same dimension or at least of tires having maximum axial widths of rotation. Given the multiplicity of dimensions of existing tires and wheels, the increase in the number of dimensions created, and given the multiplicity of structures used in said dimensions and the multiplicity of the stiffness of sidewalls which results therefrom, the known devices do not permit rational, economic use for the finishing of mounted assemblies which can be delivered to the manufacturers.